1. Field of the Invention
The present invention relates to an exposure apparatus for manufacturing devices having minute patterns, such as semiconductor chips (like ICs, LSIs, and the like), liquid crystal panels, CCDs, thin-film magnetic heads, micro-machines, and so forth.
2. Description of the Related Art
With exposure processing using semiconductor exposure apparatuses, change in magnification of the projection optical system and reticle due to exposure heat, and change in focal point of the projection optical system, are calculated from exposure results, and change coefficients are calculated from the amount of heat and the like applied to the projection optical system and reticle during the exposure process. Now, in a case of subjecting a projection optical system and reticle to exposure processing, and calculating a heat change coefficient from the exposure load and exposure results, a change coefficient for both the projection optical system and reticle together can be obtained. On the other hand, in a case of periodically measuring the amount of change between exposure processes using a so-called reticle reference plate disposed at an optically equivalent position as that of the reticle, from which a heat change coefficient is calculated, a change coefficient can be obtained for the projection optical system alone.
Minute devices of recent years require high-precision change correction regarding magnification, focal position, and so forth. Also, there is a need for even stricter restriction on the amount of fluctuation permitted for each correction value. On the other hand, the amount of time allowed for measurement processes other than the exposure process is being reduced, in order to improve productivity.